Method of Securing Pipe Elements End to End

ABSTRACT

A method of joining pipe elements in end to end relation using mechanical pipe couplings. The couplings have a plurality of segments attached end to end surrounding a central space. The segments have arcuate surfaces adapted to interface with the outer surfaces of the pipe elements. The method includes inserting end portions of the pipe elements into the central space and then drawing the coupling segments toward one another so as to engage the arcuate surfaces of the segments with the outer surfaces of the pipe elements.

CROSS REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. application Ser. No.11/485,921, filed Jul. 13, 2006, which is a divisional of U.S.application Ser. No. 11/124,781, filed May 9, 2005, now U.S. Pat. No.7,086,131, which is based on and claims priority to U.S. ProvisionalApplication No. 60/571,596, filed May 14, 2004.

FIELD OF THE INVENTION

This invention concerns methods of securing pipe elements in end to endrelation using pre-assembled mechanical pipe couplings, includingcouplings that are deformable to conform to pipe elements therebyfacilitating assembly of the pipe joint.

BACKGROUND OF THE INVENTION

Mechanical couplings for joining pipe elements together end-to-endcomprise interconnectable segments that are positionablecircumferentially surrounding the end portions of co-axially alignedpipe elements. The term “pipe element” is used herein to describe anypipe-like item or component having a pipe like form. Pipe elementsinclude pipe stock, pipe fittings such as elbows, caps and tees as wellas fluid control components such as valves, reducers, strainers,restrictors, pressure regulators and the like.

Each mechanical coupling segment comprises a housing having arcuatesurfaces which project radially inwardly from the housing and engageplain end pipe elements or circumferential grooves that extend aroundeach of the pipe elements to be joined. Engagement between the arcuatesurfaces and the pipe elements provides mechanical restraint to thejoint and ensures that the pipe elements remain coupled even under highinternal pressure and external forces. The housings define an annularchannel that receives a gasket or seal, typically an elastomeric ringwhich engages the ends of each pipe element and cooperates with thesegments to provide a fluid tight seal. The segments have connectionmembers, typically in the form of lugs which project outwardly from thehousings. The lugs are adapted to receive fasteners, such as nuts andbolts, which are adjustably tightenable to draw the segments toward oneanother.

To ensure a good fit between the couplings and the pipe elements, thearcuate surfaces on prior art couplings have a radius of curvature thatis substantially matched to the radius of curvature of the outer surfaceof the pipe element that it is intended to engage. For couplings usedwith grooved pipe elements, the radii of curvature of the arcuatesurfaces are smaller than the radii of curvature of the outer surfacesof the pipe elements outside of the grooves so that the arcuate surfacesfit within and engage the grooves properly.

Methods of securing pipe elements in end to end relation according tothe prior art comprise a tedious and time consuming installation processwhen mechanical couplings are used. Typically, the coupling is receivedby the technician with the segments bolted together and the ring sealcaptured within the segments' channels. The technician firstdisassembles the coupling by unbolting it, removes the ring seal,lubricates it (if not pre-lubricated) and places it around the ends ofthe pipe elements to be joined. Installation of the ring seal requiresthat it be lubricated and stretched to accommodate the pipe elements, anoften difficult and messy task, as the ring seal is usually stiff andthe lubrication makes manual manipulation of the seal difficult. Withthe ring seal in place on both pipe elements, the segments are thenplaced one at a time straddling the ends of the pipe elements andcapturing the ring seal against them. During placement, the segmentsengage the seal, the arcuate surfaces are aligned with the grooves, thebolts are inserted through the lugs, the nuts are threaded onto thebolts and tightened, drawing the coupling segments toward one another,compressing the seal and engaging the arcuate surface within thegrooves.

As evident from the previous description, installation of mechanicalpipe couplings according to the prior art requires that the techniciantypically handle at least seven individual piece parts (and more whenthe coupling has more than two segments), and must totally disassembleand reassemble the coupling. Significant time, effort and expense wouldbe saved if the technician could install a mechanical pipe couplingwithout first totally disassembling it and then reassembling it, pieceby piece.

SUMMARY OF THE INVENTION

The invention concerns a method of securing facing end portions of pipeelements together in end-to-end relationship. The end portions of thepipe elements have an outer surface of substantially cylindricalprofile. The coupling has a plurality of coupling segments attached toone another end-to-end surrounding a central space. The couplingsegments have arcuate surfaces adapted to interface with the outersurfaces of the pipe elements. The method comprises:

(a) inserting the end portions of the pipe elements into the centralspace; and

(b) drawing the coupling segments towards one another so as to engagethe arcuate surfaces with the outer surfaces of the pipe elements.

The method according to the invention may also include deforming thecoupling segments so as to conform the curvature of the arcuate surfacesof the coupling segments to the outer surfaces of the pipe elements.

In some embodiments, each of the pipe elements may have acircumferential groove positioned proximate the pipe element endportion. The method then further comprises engaging the arcuate surfacesof the segments within the circumferential grooves of the pipe elements.The surfaces forming the grooves are also considered to be the outersurfaces of the pipe elements.

To ensure a fluid tight joint, the coupling has a seal formed of aflexible resilient ring positioned within the central space defined bythe segments. When a seal is present, the method includes inserting theend portions of the pipe elements into the ring.

The ring may comprise a tongue extending circumferentially around thering and projecting radially inwardly. The method then further comprisesengaging the end portions of the pipe elements with the tongue uponinsertion of the end portions into the central space.

The ring may further comprise a pair of lips positioned on oppositesides of the tongue and extending circumferentially around the ring. Themethod then further comprises engaging each of the end portions of thepipe elements with one of the lips upon insertion of the end portionsinto the central space.

When a ring seal is present, the method may also comprise supporting thecoupling segments in spaced apart relation to one another on an outersurface of the ring.

The coupling may also comprise a lug positioned at each end of each thesegment. The lugs on one segment are in facing relation with the lugs onanother segment. The lugs receive adjustably tightenable fastenersconnecting the segments to one another. Drawing of the coupling segmentstowards one another is effected by tightening the fasteners.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1-1B are longitudinal cross-sectional views illustrating a methodof attaching pipe elements in end to end relation according to theinvention;

FIGS. 2 and 3 are partial cross-sectional views of the pipe couplingshown in FIG. 1;

FIGS. 4 and 5 are perspective views, partially cut away, of seals usedwith pipe couplings according to the invention;

FIGS. 6-7 and 8 are axial views of various pipe coupling embodimentsaccording to the invention;

FIGS. 7A and 9-13 are longitudinal sectional views of pipe couplingembodiments according to the invention;

FIG. 14 is a perspective view of a pipe coupling according to theinvention;

FIG. 15 is a side view of the pipe coupling shown in FIG. 14;

FIG. 16 is a cross-sectional view taken at line 16-16 in FIG. 14;

FIG. 17 is an axial view, partially cut away, of pipe couplingembodiment according to the invention;

FIG. 18 is an axial view of a pipe coupling embodiment according to theinvention;

FIG. 19 is an axial view of a pipe coupling embodiment according to theinvention;

FIG. 20 is an axial view, partially cut away, of a pipe couplingembodiment according to the invention;

FIG. 21 is a partial sectional view of the pipe coupling shown in FIG.20;

FIG. 22 is an axial view, partially cut away, of a pipe couplingembodiment according to the invention;

FIG. 23 is an axial view of a pipe coupling embodiment according to theinvention; and

FIG. 24-26 are axial views of a pipe coupling embodiments according tothe invention.

DETAILED DESCRIPTION OF THE EMBODIMENTS

FIGS. 1 and 2 show a pipe coupling 10 according to the invention.Coupling 10 is formed from coupling segments 12 and 14 which areinterconnectable with one another to straddle end portions 16 a and 18 aof pipe elements 16 and 18 to secure the pipe elements together inend-to-end relationship. The end portions of the pipe elements haverespective outer surfaces 20 and 22 of substantially cylindricalprofile.

Interconnection of the coupling segments 12 and 14 is effected byconnection members, preferably in the form of lugs 24 and 26 best shownin FIG. 2. The lugs are preferably positioned at each end of eachsegment and project outwardly from the segments. Lugs 24 and 26 arepositioned in facing relation to one another and adapted to receivefasteners, preferably in the form of bolts 28 and nuts 30 which areadjustably tightenable and cooperate with the lugs 24 and 26 foradjustably connecting the coupling segments to one another as discussedin further detail below.

As best shown in FIG. 1, each segment 12 and 14 comprises a pair ofarcuate surfaces 32 and 34. The arcuate surfaces are in spaced apartrelation to one another and preferably project radially inwardly towardthe pipe elements 16 and 18. The surfaces extend from a housing 36having sidewalls 38 joined to a backwall 40, the sidewalls and backwallforming a channel 42 that receives a seal 44.

Examples of seals 44 are shown in FIGS. 4 and 5. Seal 44 is preferably aflexible, resilient ring formed from elastomeric material. The seal mayhave lips 46 that use the internal pressure within the pipes to increasethe sealing force between the seal and the outer surfaces 20 and 22 ofthe pipe elements 16 and 18. As shown in FIG. 5, seal 44 may also have atongue 48 positioned between the lips 46, the tongue extendingcircumferentially around the seal and projecting radially inwardly.Tongue 48 provides a stop surface that engages the ends of pipe elements16 and 18 to ensure proper positioning of the seal 44 relatively to thepipe elements as described in detail below. Engagement of the pipeelements with tongue 48 also effects alignment of the arcuate surfaceswith the grooves (if present), or with alignment marks on the outsidesurface of the pipe elements.

As illustrated in FIG. 2, arcuate surfaces 32 and 34 have radii ofcurvature 50 greater than the radii of curvature 52 of the outersurfaces 20 and 22 of pipe elements 16 and 18. Furthermore, the arcuatesurfaces 32 subtend an angle 54 of less than 180°. Angles 54 betweenabout 40° and about 179° are practical. As a result of this arcuatesurface geometry, segments 12 and 14 may be pre-assembled separated fromone another such that pipe elements 16 and 18 may be inserted directlyinto the coupling 10 as shown in FIG. 1 without first disassembling thecoupling. This feature provides a significant advantage over prior artcouplings which must be assembled onto the pipe ends piece by piece.Joining of the pipe ends with a coupling 10 according to the inventionproceeds much more smoothly and quickly than with prior art couplingsbecause the technician handles fewer pieces and does not have to threadnuts onto bolts. In the embodiment shown in FIG. 1, the seal 44 has anouter diameter 56 sized to hold the coupling segments 12 and 14 inspaced apart relation sufficient to allow the pipe ends to be insertedas described above. The seal inner diameter 58 is sized to receive theend portions 16 a and 18 a of the pipe elements simply by pushing thecoupling over the pipe element or by inserting the pipe elements intothe coupling. Other embodiments having different features for supportingthe segments in spaced relation are described below.

After both pipe elements 16 and 18 are inserted into coupling 10 asshown in FIG. 1A, nuts 30 are tightened (see also FIG. 2). The nuts 30cooperate with their bolts 28 to draw the arcuate surfaces 32 and 34 onsegment 12 toward those on segment 14. Tightening of the nuts exerts aforce on the lugs 24 and 26 which brings the segments into contact withthe pipe elements and causes the segments 12 and 14 to deform such thatthe radius of curvature 50 of the arcuate surfaces 32 and 34substantially conforms to the radius of curvature 52 of the pipeelements 16 and 18. This action is illustrated by comparing FIGS. 2 and3 and 1A and 1B, wherein the gap 60 between the arcuate surfaces and thepipe outer surfaces diminishes as the arcuate surfaces are brought intoengagement with the outer surfaces of the pipe ends. Deformation of thesegments 12 and 14 is preferably substantially elastic, allowing thesegments to spring back substantially to their original shape when thenuts 30 are loosened, thereby permitting the coupling 10 to be reused inthe manner according to the invention as described herein. The segmentsmay also be designed to have significant plastic deformation, whereinthe deformation imparts a permanent set to the segments. For practicalcouplings, there will generally be some degree of both plastic andelastic deformation occurring in the segments as a result of tighteningthe fasteners. Additionally, when the segments 12 and 14 are in theundeformed state (FIG. 2), the lugs 24 and 26 may be angularly orientedin relation to one another. Relative angles 62 up to about 10° arepractical. As shown in FIG. 3, the relative angular orientation of thelugs 24 and 26 is reduced as the segments are deformed, and the geometrymay be designed such that the lugs are substantially parallel once thearcuate surfaces 32 and 34 substantially conform to the outer surfaces20 and 22. This is preferred because, when fully tightened, the bolthead and nut will be in substantially flat contact with the lugs,thereby avoiding induced bending moments in the bolts which can causepermanent deformation of the bolts. The seal 44 is also deformed by thisprocess, as shown in FIG. 1B, with the lips 46 coming into fullengagement with the pipe element outer surfaces 20 and 22. Because theseal 44 is substantially incompressible, it must be provided with spaceinto which it may expand when compressed by the segments. This space isprovided by a concavity 64 positioned in the backwall 40 between thesidewalls 38. Concavity 64 may take virtually any practical shape andallows for volume change of the seal when it is heated or exposed tofluids thereby distributing the deformation of the seal more evenly overits circumference and mitigating the tendency of the seal to extrudeoutwardly from between the segments between the lugs. The concavity alsoprevents tongue 48, if present, from being forced between the ends ofthe pipe elements and impede flow therethrough.

As shown in FIGS. 2 and 3, for the preassembled coupling 10, it isadvantageous to hold nuts 30 in a position on bolts 28 that willmaintain the segments 12 and 14 in the desired spaced apart relation asdetermined by contact between the segments and the seal 44. This isconveniently accomplished by deforming the threads 29 of bolts 28,preferably by staking. Staking the bolts hinders the rotation of thenuts and prevents them from unscrewing from the bolts under the effectof vibration, for example, during shipping, and keeps the coupling inthe preassembled state with all of its parts together prior toinstallation. The staking is readily overcome when the nuts aretightened with a wrench.

The bending stiffness of the segments may be tuned to control the amountof force necessary to deform them in order to reduce the requiredassembly torque and mitigate galling between the nut and the lug. Asshown in FIG. 6, sections of increased bending flexibility 66 may beformed in the housing 36 of the segments 12 and 14 by reducing the areamoment of inertia of the segment. This reduction is preferably achievedby adding one or more cut-outs 68 in either or both the backwall 40 andthe arcuate surfaces 32 and 34.

Alternately, as shown in FIG. 7, the segments may have arcuate surfaces32 and 34 (not shown) comprising inwardly projecting teeth 69. Teeth 69engage outer surfaces of the pipe elements to provide mechanicalrestraint, and are especially advantageous when used with plain end pipeelements. Teeth 69 may be substantially continuous, as shown on segment14, or intermittent, as shown on segment 12. Single teeth, preferablefor small couplings, are also feasible. As shown in FIG. 7A, teeth 69may also be arranged in pairs on opposite sides of the segment toincrease the mechanical restraint provided by the coupling.

Although couplings according to the invention are described above ascomprised of two segments, this is by way of example only. Couplingswith more than two segments are feasible and preferred for largerdiameter pipes due to the manufacturing costs, as reducing the size ofthe segments is economically advantageous. A further advantage is thatthe spacing between the lugs is reduced, requiring fewer turns of thenut and shorter bolts. Standard depth sockets may thereby be used duringinstallation. FIG. 8 shows an example of a coupling embodiment 72 havingfour segments 74 similar to those described above.

Couplings have thus far been shown wherein all of the arcuate surfaceshave substantially the same radius of curvature. Whereas such aconfiguration is appropriate for joining pipes having substantially thesame diameter to one another, FIG. 9 shows a coupling embodiment 76 forcoupling pipe elements of different diameters. Coupling 76 is formed oftwo segments 78 and 80 (although it may have more than two segments).Each segment has a first arcuate surface 82 having a first radius ofcurvature 84, and a second arcuate surface 86 having a second radius ofcurvature 88 smaller than the first radius of curvature 84. This allowscoupling 76 to join a pipe element 90 having a larger diameter to a pipeelement 92 having a smaller diameter. Analogous to the couplingsdescribed above, the radius of curvature 84 is greater than the radiusof curvature of the outer surface of pipe element 90, and the radius ofcurvature 88 is greater than the radius of curvature of the pipe element92. This geometric relationship allows the pipe elements 90 and 92 to beinserted into a pre-assembled coupling 76 and achieve the advantages ofthe invention. The coupling segments 78 and 80 deform upon theapplication of force by adjustable connection members to conform theradii of curvature to the outer surface of the pipe elements.

In a preferred embodiment, shown in FIG. 10, the inwardly projectingarcuate surfaces 32 and 34 of coupling 10 engage grooves 94 formed inthe outer surfaces 20 and 22 of pipe element end portions 16 a and 18 a.Interaction between the arcuate surfaces 32 and 34 with their respectivegrooves 94 permits the coupling to provide relatively high end restraintto withstand forces caused by internal pressure or external loads. Toobtain higher end restraint, it is found useful to add a second set ofarcuate surfaces that interact with a second set of grooves in the pipeelements. This embodiment is illustrated in FIG. 11, wherein a coupling96 is comprised of segments 98 and 100, each segment having two pairs ofarcuate surfaces 102 and 104 that project inwardly from the segments.The arcuate surface pairs are in substantially parallel, spaced relationto one another and engage pairs of grooves 106 in the surfaces of thepipe elements 108 and 110 which they connect together.

In another embodiment, shown in FIG. 12, couplings according to theinvention such as 10 may be used with pipe elements 112 and 114 havingraised circumferential shoulders 116 that are engaged by the arcuatesurfaces 32 and 34 of the segments 12 and 14. Alternately, as shown inFIG. 13, a coupling 118 according to the invention having segments 120and 122 with respective arcuate surfaces 124 and 126 is used with pipeelements 128 and 130 having flared end portions 132 and 134. Note thatin the example embodiments shown in FIGS. 9-13, the seal 44 has thetongue 48 which is effectively used to position the pipe ends within thecoupling upon insertion, the tongue acting as a pipe stop to aid inlocating the pipe ends at the proper depth within the couplings.

Another coupling embodiment 136 is shown in FIG. 14. Coupling 136 iscomprised of two segments 138 and 140 from which lugs 142 and 144extend, the lugs cooperating with fasteners 146 to act as connectionmembers for adjustably connecting one coupling segment to another. Asdescribed above, each segment has a pair of arcuate surfaces 148, 150,each preferably projecting radially inwardly from the segments. Thearcuate surfaces subtend an angle 152 less than 180° and have a radiusof curvature 154 greater than the radius of curvature of the pipeelements which the coupling is to join together. Anti-rotation teeth 70are positioned adjacent to the arcuate surfaces and project radiallyinwardly to engage the pipe elements and provide torsional rigidity.

As best shown in FIG. 15, each segment 138 and 140 has a pair ofangularly oriented surface portions 156 and 158 located adjacent to eachof the lugs 142 and 144. As illustrated, the slope of surface portion156 may be opposite to the slope of surface portion 158 on each segment.(Both surfaces could also be sloped in the same direction as well.) Thisopposite slope relationship between the surfaces on a segment results insurfaces having compatible slopes being positioned in facing relation ina pre-assembled coupling as shown in FIG. 15. When the fasteners 146 aretightened, conforming the arcuate surfaces to the outer surfaces of thepipe elements, the angular surface portions 156 and 158 on each segmentengage and slide relatively to one another, causing the segments to drawtogether and rotate relatively to one another in opposite directionsabout an axis 160 oriented substantially perpendicularly to the axis ofthe pipe elements being joined. These motions of the segments 138 and140 causes the arcuate surfaces 148 and 150 to engage grooves in thepipe elements and adds rigidity to all axes of the joint as previouslydescribed. For coupling segments having surface portions with the sameslopes, the couplings move along the pipe in opposite directionsrelatively to one another with similar effect.

As shown in cross section in FIG. 16, the segments 138 and 140 formingthe coupling 136 have a channel 162 defined by a housing 164. Thehousing is formed from a back wall 166 and sidewalls 168, and receives aseal 170 which is sized to position the segments 138 and 140 in spacedapart relation so as to allow insertion of pipe elements into thepre-assembled coupling shown in FIG. 14. A concavity 172 is provided inthe back wall to provide a space for volume change of the seal when itis heated or exposed to fluids as well as to prevent tongue 48 frombeing forced between the ends of the pipe elements and impede flowtherethrough due to compression of the seal.

In another coupling embodiment, shown in FIG. 17, the coupling 174 againis comprised of at least two coupling segments 176 and 178, each havinginwardly projecting arcuate surfaces 180 as described above. However,arcuate surfaces 180 have notches 182 and 184 positioned at oppositeends. The notches 182 and 184 provide clearance at the 3 o'clock and 9o'clock positions of the coupling where it is most needed to permit pipeelements to be inserted into the pre-assembled coupling 174. Theavailability of increased clearance at these locations allows thecoupling segments 176 and 178 to be spaced closer to one another in thepre-assembled configuration than would be the case if the clearance wasnot available at the ends of the surfaces. By having the segments of thepreassembled coupling closer together, the amount of deformationrequired to conform the arcuate surfaces to the pipe element outersurface is reduced and thereby the energy required to tighten thefasteners.

Another coupling embodiment 192 according to the invention is shown inFIG. 18. Coupling 192 comprises an arcuate band 194 surrounding acentral space 196. Band 194 has opposite ends 198 and 200 positioned infacing relation to one another. Ends 198 and 200 are in spaced relationin the pre-assembled coupling and have connection members mountedthereon, preferably in the form of projecting lugs 202 and 204 adaptedto receive a fastener such as bolt 206 and nut 208. The bolt and nutcooperate with the lugs to deform the band 194 and bring the ends 198and 200 toward one another after pipe elements have been inserted intothe central space 196 for coupling in end-to-end relationship. Band 194has a pair of arcuate surfaces 210, only one of which is visible in thefigure. The arcuate surfaces are in spaced relation lengthwise of oneanother as illustrated in FIG. 10 and described above for otherembodiments. The arcuate surfaces 210 have a greater radius of curvaturethan the outer surface of the pipe ends that the coupling is to jointogether. This geometric configuration, and the separation of the ends198 and 200 allows the pipe elements to be inserted into central space196. Upon tightening of the nut 208 the band 194 is deformed such thatthe radius of curvature of the arcuate surfaces 210 are forced toconform with the radius of curvature of the outside surface of the pipeelements which they engage. Note that in the preassembled state,projecting lugs 202 and 204 are preferably angularly oriented withrespect to one another, having a relative angle 212 up to about 20°.Tightening of the fastener draws the lugs toward each other, and resultsin decreasing the relative angle 212, preferably to the point whereinthe lugs are substantially parallel to one another. This is particularlyadvantageous for a flexible coupling which does not depend upon the pipeelements to form a reaction point to cause the deformation incombination with the bolts, the friction incurred at the reaction pointsinhibiting flexibility.

Coupling 192 includes a seal 214 positioned within the band 194 betweenthe arcuate surfaces 210. Seal 214 may be similar to those illustratedin FIGS. 4 and 5 and sized to receive the pipe elements for creating afluid tight seal when the band is deformed.

The bending flexibility of coupling 192 may be adjusted by reducing thearea moment of inertia of band 194. Such adjustments may be effected bypositioning cut-outs 216 in the band. Alternately, as shown in FIG. 19,a hinge 218 may be provided between the ends 198 and 200. Hinge 218 ispreferably positioned equidistant from the ends of the band and providesinfinite bending flexibility, reducing the torque needed on the fastenerto draw the ends 198 and 200 toward one another. The band 194 will stilldeform as the arcuate surfaces 210 engage the outer surfaces of pipeelements to conform the radii of the surfaces with that of the pipeelement outer surfaces. When the hinge is present, the seal 214 is sizedso as to maintain the lugs 202 and 204 in spaced relation so that pipeelements may be inserted. For both the hinged and hingeless versions ofthe coupling described above, the arcuate surfaces preferably projectradially inwardly from the band and may have different radii ofcurvature from each other, as illustrated in FIG. 9, to allow thecoupling 192 to be used to join pipes having different diameters.

FIG. 20 illustrates a pre-assembled coupling 220 that does not depend onthe seal 222 to maintain its segments 224 and 226 in spaced apartrelation and ready to receive pipe elements such as 228. Coupling 220has spacers 230 that extend between segments 224 and 226 and maintainthe segments in spaced apart relation. In this example embodiment, thespacers 230 comprise collapsible tubes 232 that are positioned betweenfacing lugs 234 and 236 that extend from the segments. Tubes 232 arepreferably thin walled and circular in cross section and are arrangedcoaxially surrounding the fasteners 238. The tubes may be made oflightweight metal or a polymer material such as polypropylene and mayhave score lines 240 in their surface to create weakened regions thatfacilitate collapse of the tube under compressive loads applied by thefasteners 238. Other materials, such as cardboard and rubber are alsofeasible. The tubes are designed to be strong enough to support thesegments in spaced relation during shipping, handling and installation,but collapse at a predetermined compressive load that a technician mayapply, preferably by manually tightening the fasteners with a wrench.

In use, pipe elements to be joined end-to-end are inserted between thesegments 224 and 226. Fasteners 238 are then tightened to draw thesegments toward each other and into engagement with the pipe elements.Tightening of the fasteners places the tubes 232 under a compressiveload, and the tubes buckle and collapse as shown in FIG. 21 when thepredetermined load is achieved to allow the segments to move toward oneanother and engage the pipe elements to effect the joint.

Spacers positioned between the segments may be used with any type ofmechanical coupling. Note that in FIGS. 20 and 21, the segments 224 and226 have arcuate surfaces 242 with a radius of curvature that issubstantially the same as the radius of curvature of the outer surfaceof pipe element 228 which they are designed to engage. To provideclearance between the pipe element 228 and the segments allowing thepipe element to be inserted into the coupling while still maintaining areasonable fastener length, notches 244 and 246 are positioned atopposite ends of the arcuate surfaces 242 as best shown in FIG. 20. Thenotches provide clearance at the 3 o'clock and 9 o'clock positions ofthe coupling to permit pipe elements to be inserted into thepre-assembled coupling 220.

FIG. 22 illustrates another coupling embodiment 254 having spacers 230between segments 256 and 258 comprising the coupling. In this example,the spacers 230 comprise tubes 260 again positioned coaxially withfasteners 262 and between facing lugs 264 and 266 projecting from thesegments. Tubes 260 have corrugations 268 which facilitate theircollapse when compressive load is applied by tightening the fasteners.Note that the segments 256 and 258 are similar to those described abovewith respect to FIGS. 1 and 2, wherein the arcuate surfaces of thesegments have a greater radius of curvature than the pipe elements.

Another example of a spacer for maintaining coupling segments in spacedrelation is shown in FIG. 23. Coupling 270 is comprised of segments 272and 274 having outwardly projecting lugs 266 and 268 positioned infacing relation when the coupling is pre-assembled. The segments areheld together by fasteners 280 extending between the lugs. Spacers 282,preferably in the form of block-shaped bodies 284, are positionedbetween the lugs 266 and 268. The bodies 284 are removable from betweenthe lugs to allow the fasteners to be tightened and draw the segmentsinto engagement with pipe elements being joined.

Bodies 284 may be releasably attached to the segments, for example, heldby friction between the lugs 266 and 268. Flexible, resilient materialsare particularly advantageous for forming the bodies because bodies madefrom such materials provide adequate strength and stiffness to maintainthe couplings in spaced apart relation during rough handling but may bereadily deformed for easy removal as required. If polymer materials areused to form the bodies they may be adhered to the lugs by heat fusingor by adhesives which afford a releasable bond between the bodies andthe segments.

FIG. 24 illustrates a non-deformable coupling embodiment 286 that usesspacers 288 to maintain coupling segments 290 and 292 in spaced apartrelation so that pipe elements may be inserted between them in thepreassembled state shown. Coupling 286 has no notches or other featuresthat provide clearance facilitating inserting pipe elements into end toend relation between the segments, but relies on the spacers to providesufficient separation for adequate clearance. The spacers 288 may besimilar to those described above.

Spacers according to the invention may also be used with various othertypes of couplings. As shown in FIG. 19, a spacer 288 may be used withthe hinged coupling embodiment 192 to keep the lugs 202 and 204 inspaced apart relation so that pipe elements may be inserted. Although atubular spacer is illustrated, it is understood that any of the spacersdescribed herein are feasible for use with this coupling.

FIG. 25 illustrates an adapter coupling 294 for joining flanged pipe tonon-flanged pipe, for example, grooved or plain end. Coupling 294comprises coupling segments 296 and 298, each of which has a radiallyextending flange 300 on one side and a arcuate surface 302 on theopposite side. Segments 296 and 298 are held in spaced apart relation byspacers 304, which may comprise a collapsible tubular spacer 306 or aremovable spacer 308, or other types of spacers described herein.

FIG. 26 illustrates further types of spacer embodiments 310 feasible formaintaining coupling segments 312 and 314 in spaced apart relation.Spacers 310 comprise spring elements which deform, preferablysubstantially elastically, when subjected to a compression force by thefasteners 316. Spring elements may take any of a number of forms, forexample, a rubber cylinder 318 or a coil spring 320. The use of springelements for spacers allows for fine control of the forces required todraw the segments toward one another and also facilitates the reuse ofthe couplings when the deformation of the spring elements issubstantially elastic.

Deformable mechanical pipe couplings according to the invention providefor rapid and sure installation creating a pipe joint while avoiding theneed to partially or totally disassemble and then reassemble thecoupling and handle the individual piece parts.

1. A method of securing facing end portions of pipe elements together inend-to-end relationship, wherein said end portions of said pipe elementshave an outer surface of substantially cylindrical profile, said methodcomprising: providing a coupling having a plurality of coupling segmentsattached to one another end-to-end surrounding a central space, saidcoupling segments having arcuate surfaces adapted to interface with theouter surfaces of said pipe elements; inserting said end portions ofsaid pipe elements into said central space; and drawing said couplingsegments towards one another so as to engage said arcuate surfaces withsaid outer surfaces of said pipe elements.
 2. The method according toclaim 1, further comprising deforming said coupling segments so as toconform the curvature of said arcuate surfaces of said coupling segmentsto said outer surfaces of said pipe elements.
 3. The method according toclaim 1, wherein each of said pipe elements has a circumferential groovepositioned proximate said end portion, said method further comprisingengaging said arcuate surfaces of said segments within saidcircumferential grooves of said pipe elements.
 4. The method accordingto claim 1, wherein said coupling further comprises a seal formed of aflexible resilient ring positioned within said central space, saidmethod including inserting said end portions of said pipe elements intosaid ring.
 5. The method according to claim 4, wherein said ringcomprises a tongue extending circumferentially around said ring andprojecting radially inwardly, said method further comprising engagingsaid end portions of said pipe elements with said tongue upon insertionof said end portions into said central space.
 6. The method according toclaim 5, wherein said ring further comprises a pair of lips positionedon opposite sides of said tongue and extending circumferentially aroundsaid ring, said method further comprising engaging each of said endportions of said pipe elements with one of said lips upon insertion ofsaid end portions into said central space.
 7. The method according toclaim 4, further comprising supporting said coupling segments in spacedapart relation to one another on an outer surface of said ring.
 8. Themethod according to claim 1, wherein said coupling further comprises alug positioned at each end of each said segment, said lugs on one saidsegment being in facing relation with said lugs on another said segment,said lugs receiving adjustably tightenable fasteners connecting saidsegments to one another, said drawing said coupling segments towards oneanother comprising tightening said fasteners.
 9. A method of securingfacing end portions of pipe elements together in end-to-end relationshipusing a coupling having a plurality of coupling segments attached to oneanother end-to-end surrounding a central space, said coupling segmentshaving arcuate surfaces adapted to interface with the outer surfaces ofsaid pipe elements, and wherein said end portions of said pipe elementshave an outer surface of substantially cylindrical profile, said methodcomprising: inserting said end portions of said pipe elements into saidcentral space; and drawing said coupling segments towards one another soas to engage said arcuate surfaces with said outer surfaces of said pipeelements.
 10. The method according to claim 9, further comprisingdeforming said coupling segments so as to conform the curvature of saidarcuate surfaces of said coupling segments to said outer surfaces ofsaid pipe elements.
 11. The method according to claim 9, wherein each ofsaid pipe elements has a circumferential groove positioned proximatesaid end portion, said method further comprising engaging said arcuatesurfaces of said segments within said circumferential grooves of saidpipe elements.
 12. The method according to claim 9, wherein saidcoupling further comprises a seal formed of a flexible resilient ringpositioned within said central space, said method further comprisinginserting said end portions of said pipe elements into said ring. 13.The method according to claim 12, wherein said ring comprises a tongueextending circumferentially around said ring and projecting radiallyinwardly, said method further comprising engaging said end portions ofsaid pipe elements with said tongue upon insertion of said end portionsinto said central space.
 14. The method according to claim 13, whereinsaid ring further comprises a pair of lips positioned on opposite sidesof said tongue and extending circumferentially around said ring, saidmethod further comprising engaging each of said end portions of saidpipe elements with one of said lips upon insertion of said end portionsinto said central space.
 15. The method according to claim 12, furthercomprising supporting said coupling segments in spaced apart relation toone another on an outer surface of said ring.
 16. The method accordingto claim 9, wherein said coupling further comprises a lug positioned ateach end of each said segment, said lugs on one said segment being infacing relation with said lugs on another said segment, said lugsreceiving adjustably tightenable fasteners connecting said segments toone another, said drawing said coupling segments towards one anothercomprising tightening said fasteners.